dmt modulation cpe security in wifi Dsl adsl cpe conf

DMT modulation, CPE,
Security in WIFI

Objectives
- Components of Broadband Technology & Their Functions
- Customer Premises components and network
- Service Provider side BB N/w
- DSLAM Details
- Multiplay Broadband Services and N/w
- Fundamentals of DSL Technologies – DMT
Modulation
- ADSL Modem Configuration in Bridge and PPPoE
Mode
- Wi-Fi Configuration and Security

Broadband Network- at a glance
Access layer:
• Access layer is the one which faces the customer side
and all the access devices such as DSLAM/OLT,
CPE(MODEM), SetTop box , etc. , gets connected.
Aggregation layer:
• As name depicts , this layer aggregates all the access
traffic and pass it to the Core or gateway.
Core/Gateway:
• All the Aggregated traffic is assigned Qos/traffic policy
and make its way to the global internet via the gateway.

Broadband Connectivity
© BHARAT SANCHAR NIGAM LIMITED

Broadband Components
Customer Premises Equipment(CPE)
Digital Subscriber Line Access
Multiplexer (DSLAM)
LAN Switches: for aggregating DSLAM
Broadband Remote Access Server
(BRAS)
RADIUS and LDAP (SSSC- Subscriber
Service Selection System)
Provisioning System

3
0
Brief Functions of DSL Components
DSL CPEs: At customer premises. On one end it connects
telephone cable coming from exchange via splitter. At the
other end, it connects to PC through Ethernet / USB Port.
DSLAM: called as DSL Access Multiplexer. It has a built
in splitter which splits voice and data. While voice
followsthe normal conventional path through exchange,
data is aggregated and up linked through Ethernet Port
(Gigabit Ethernet for 480 port and Fast Ethernet for
lower DSLAM)
LAN Switch: For aggregating multiple DSLAM and
providing a common uplink to the core.

Brief Functions of DSL Components….
 BRAS: called as Broadband Remote Access
Server. First intelligent device in the whole
chain. It terminates the customer session,
authenticates, allott IP addresses and keeps
track of user session for billing along with
RADIUS.
 SSSS: Called as Subscriber Service Selection
System. When customer logs in he will be
welcomed with this customized screen from
where he can select various range of service.
This provides on demand service without
manual intervention.

 RADIUS(Remote Authentication Dial-in User Service): This
in conjunction with BRAS authenticates customer, upload
customer profile in the SSSS and keeps track of billing.
 LDAP(Lightweight Directory Access Protocol): It stores
customer database viz username, password and the
default services that it can subscribe to.
 Provisioning: This is the most critical components for
ensuring quick delivery of service. It ensures end-to-end
provisioning of service right from DSL CPEs to DSLAM to
Switch to BRAS to LDAP.
Brief Functions of DSL Components….

3
3
Requirement at Customer End
Landline Telephone
Computer of minimum configuration, with
10/100 Mbps Ethernet Card
DSL Modem + Splitter
PPPoE software to be loaded in the Client
Broadband Account (Username and
Password)

Central Office
Home/Office
ADSL
CPE
Curb
ADSL up to 5Km
SHDSL up to 5Km
SHDSL
Splitter
DSLAM
Data switch
Voice Switch
POTS
2 wire
2 wire
ADSL Deployment

Installation of Broadband Modem at
Customer Premises
Connect the Modem to the Power
Supply Adapter
Next Connect the Ethernet Cable from
the Modem Ethernet Port to the Ethernet
Port on the PC

Installation of Broadband Modem at
Customer Premises
 Connect from the ADSL Splitter Port Marked as LINE to the BSNL Wall Socket
 Using the RJ-11 Cable supplied, Connect the ADSL Port on the Modem to the
Splitter marked as “MODEM”.
 Then connect then Phone on to the Splitter marked “PHONE” using one more RJ-
11 Cable.
 Over all the connectivity looks as below

Modem Power On and LED Status
 Using the ON/Off Switch Power on the Modem.
 Once Powered on, Power LED will start glowing Green
 After initial self test the WLAN LED will be solid Green
 The Ethernet LEDs if they are connected to the PCs will
be Solid Green.
 The USB LEDs if they are connected to the PCs will be
Solid Green.
 The DSL LED will blinking Green during the Training or
Handshake Phase and once trained or Handshake is
complete, it will be Solid Green.
 INTERNET LED will blink green once the Modem gets IP
Address on its WAN Side .

Slide No. 38 of
DSLAM
Digital Subscriber Line Access Multiplexer.
Equipment located at a phone company’s central office (CO).
Subscriber DSL data over existing copper telephone lines is
mutiplexed to a single high speed optical fiber Ethernet line. (during
upload)

Slide No. 39 of
DSLAM
Subscriber’s data is demultiplexed from the stream received at
optical ethernet port and forwarded towards respective subscribers
DSL port. (during download)

Slide No. 40 of 51
DSLAM
Intermixes voice frequency signals and high-speed
into a customer’s DSL line.
DSL data traffic
Separates incoming phone and data signals and
onto the appropriate carrier’s network.
directs them

Slide No. 41 of
DSLAM
Voice calls are sent
DSLAM.
to the PSTN, and data are sent to the
DSLAM is connected to Internet Backbone for access to World
Wide Web and other applications using access and core Broadband
Network Elements

Slide No. 42 of
BB Multi-Play
Multi-Play is the convergence of voice, video and data
services.
Switched Broadcast
Broadband
IP
Video
Data
Voice

Slide No. 43 of
TRIPLE PLAY SERVICE
The triple play service means providing the following
services to the customer
Voice
Data (Internet)
Video (IPTV
, VoD or in general live broadcast and
stored broadcasting using video streaming protocols)

Slide No. 44 of
N/W Architecture Broadband
Multiplay

Slide No. 45 of
Components of Broadband
Multiplay
ADSL CPE
DSLAM
RPR (Tier-1 Switch and Tier-2 switches in
& vice
the ring Provides connectivity to BNG
versa)
BNG – Broadband Network Gateway (Connects
Multiplay Network to NIB2 Backbone Project 1,
through L3PE)

Customer Premises Equipments
Splitter
• The filter separates out the signal for telephone i.e.
voice and data signals are segregated and vice versa.
High Pass and Low Pass Filter used at both ends, CPE
and ACCESS NE sides.
CPE(Modem /ONT)
• The CPE directs the signal to PC and TV. Service
Specific ATM PVC Values and subscribers’ secrets are
configured.
Enable security features to avoid botnet and Man in the
Middle(MITM) attacks.

DSLAM
• DSL Access Multiplexor or Demultiplexor.
• Supports PPP and ATM for xDSL services.
• Supports GE and FE connectivity for uplink, cascading,
and other types of data connectivity.
• Supports VLAN.

RPR
Resilient Packet Ring(RPR) Switch:
• The traffic from access devices and remote aggregation
devices is aggregated in RPR and forwarded to the Core
Network.
• Resilience: Proactive span protection automatically
avoids failed span within 50ms.
• Ring Topology gives the scalable option of having more
than 100 nodes in a ring.
• RPR has the ability to differentiate between low & high
priority packets.

Broadband Network Gateway
(BNG)
• It routes traffic to and from broadband remote access devices
DSLAMs /OLTs on an Internet service provider's (ISP) network.
• It works as Multi Service Edge Router(MSER).
• Service specific logical mini routers are configured in BNG
called context or routing instances.
• BNG maps the traffic coming from access networks elements
and forward to uplink L3PE VLANs IP MPLS Network through
corresponding service context.
• Authentication, Authorization and accounting processes
happen via radius servers configured logically in BNG.

Cont.
• Enforces quality of service (Qos) policies.
• Provides layer 3 connectivity and routes IP traffic
through an Internet service provider’s backbone network
to the Internet.

2
Fundamentals of DMT
Modulation
Discrete Multi-Tone modulation
Evolved from the concept of operating an array of N
relatively low-rate transceivers in parallel to achieve
an overall high rate on one line.
The N low-rate information streams are kept
separated from one another by sending them over N
separate frequency sub-bands or sub-channels, also
called sub-carriers.
DMT achieves this sub-channel arraying by utilizing
the IFFT (Inverse Fast Fourier Transform) and its
counterpart, the FFT (Fast Fourier Transform).
© BHARAT SANCHAR NIGAM LIMITED Slide No. 29 of 51

256 frequency bands of sub-carriers of 4 KHz bandwidth and
spacing of 4.3 KHz. Each sub carrier can support maximum 15
bits/Hz. Depending on signal to noise ratio for that sub carrier a
decision is taken how many bits that particular sub carrier can
support. Each sub-carrier can carry 0-15 bits/Hz/Sec. Carrier 0 for
voice, 1-5 for guard band and 6 onwards for data.
Frequency (KHz)
Voice
0 4 25 138 139
No
of
Bits
15
1104 KHz
6 37
Upstream
16
69 kHz
Upstream
Pilot Tone
Downstream
64
276 kHz
Downstream
Pilot Tone
38 255
ADSL DMT Modulation
0
GB

Frequency Spectrum of ADSL
The ADSL transmit signal consist of a large number ( up to
256) of sub-carrier located at spacing of 4.3125 KHz.
The channel 0 is for POTS , Channel 1-5 are not used to
avoid interference between voice and data.
POTS Channel - Separated by a POTS splitter
Upstream/Downstream channels separated by either FDM
using LPF/HPF or a combination of FDM and echo
cancellation .
Echo cancellation improves the BW throughput in the
downstream direction

5
Bandwidth from 0 to 1.1 MHz is divided into
256 sub carriers with each occupying 4 KHz.
Sub-carrier 0 is used for voice, 1-5 for guard
band between voice and data, 6 – 37 for
upstream data and 38 – 255 for downstream
data.
There are 32 upstream channels and 218
downstream channels.
Frequency Spectrum of ADSL

Upstream Downstream
Voice
0 4 25 138 139
Frequency (KHz)
No
of
Bits
15
dB
1104 KHz
Signal to
noise ratio
ADSL DMT Modulation

7
There are 32 upstream channels and 218
downstream channels.
 Upstream Bit rate calculation:
There are total 32 sub-bands in upstream. If we assume ideal
case then we can modulate max. 15 bits/Hz/Sec.
So, one sub-band can accommodate 15*4 Kbits/sec.
So, 32 sub-bands can accommodate 15*4*32 Kbits/sec = 1920
Kbps
 Downstream Bit rate calculation:
There are 218 sub-bands in downstream.
So, in ideal case (15 bits/Hz/Sec), bit rate will be 15*4K*218
bits/Sec = 13080 Kbps
Upstream and Downstream Bit Rate
Calculation in ADSL

ADSL2+ DMT Modulation
Downstream
0 4
No
of
Bits
15
6 37 38 255
ADSL/ADSL2
0.14MHz
Frequency
1.1MHz 2.2MHz
ADSL2+
•ADSL2+ uses 2.2 MHz bandwidth to
Carry data
511
Upstream
0
Voice
GB

ADSL 2/2+ are further improvement over ADSL
and provide greater download speed and better
range.
Due to better modulation efficiency, more
download speed is possible.
ADSL 2/2+ can re-synchronize on line at different
speed without interrupting the communication if
SNR changes due to external interference. This is
not possible withADSL.
When no communication is taking place
ADSL2/2+ can go in sleep/power saving mode
and come back to live mode automatically when
data transmission starts.
9
ADSL 2/2+

ATM
ATM stands for Asynchronous Transfer Mode. It is a
switching technique that uses time division multiplexing
(TDM) for data communications.
ATM networks are connection oriented networks for cell
relay that supports voice, video and data
communications. It encodes data into small fixed - size
cells so that they are suitable for TDM and transmits
them over a physical medium.
The asynchronous transfer mode (ATM)
protocol architecture is designed to support the transfer
of data with a range of guarantees for quality of service.
The user data is divided into small, fixed-length packets,
called cells, and transported over virtual connections.

Architecture of an ATM Network

Connection Identifiers
The valid VPI range is from 0 to 255. The valid VCI range is
from 32 to 65535.

Modem Basic Configuration
 For modem configuration, we have to login to modem
 Login to modem is possible only if PCs TCP/IP property is
properly configured
 For configuration of the Modem following Basic Configuration
Steps need to be carried out on the Modem.
 To illustrate the configuration steps
• VPI =0 and VCI=35 are used
 Ensure that PC is configured to get DHCP Address
• By Default PC should get the Following Parameters once
connected to the Modem and the Modem is Powered ON.
IP Address …………: 192.168.1.2 (If this is the Ist PC)
Subnet Mask……….: 255.255.255.0
Default Gateway…..: 192.168.1.1

Verify PCs TCP/IP Configuration
 In order to verify whether an IP Address is assigned to
the PC go the Command Prompt. Follow the steps
below.
• Start Run
• Type cmd in Open Dialog Box and then Press OK
• At the DOS Prompt type ipconfig/all. Check the PCs IP
address

Modem Configuration
 Access the Modem WEB Page by typing
http://192.168.1.1 on the Web Browser (Internet
Explorer, Netscape, google chrome, firefox etc )
 A login Prompt Pops up where you need to give
Modem User Name and Password. The User
Name and Password are “admin” and “admin”

Modes of configuration of modem
There are two ways to configure an ADSL
modem for broadband connection.
One in PPPoE (Point to Point Protocol over
Ethernet) and the another is Bridge mode.

PPPoE Mode
In this mode the modem works as router and the PPPoE
session terminates on WAN port of router. The PPPoE client is
in built in the modem .The Internal network has to use the
private IP and for Internet access NATing happens in modem. In
PPPoE mode the modem is configured in such a way that the
user id and password are stored inside the Modem. Internet
connection will be established as you switch on the Modem.
Bridge Mode
In this mode the modem works as transparent Ethernet bridge
and therefore you need to run the PPPoE client software ( for
login authentication) on your PC/server.
Both the modes can be used as per the requirement and
application.

Main Differences
PPPoE mode
1. User id and password stored inside the Modem.
2. Multiple PCs can be connected. For example most of the
basic ADSL Modems having at least one ADSL port and one
USB port. In PPPoE mode, can connect one PC to Ethernet
port and one PC to USB port which enable simultaneous
internet usage in both the PCs.
3. PPPoE mode is more secured.
Bridge Mode
1. In bridge mode user id and password to be entered in the
dialer of computer.
2. Only single PC can be connected.
3. Less secured because all the ports are open need good
firewall to avoid virus infection.

Modem Configuration
 Once successfully logged in the Modem,
the following screen will be displayed.

Modem Configuration
 To configure the Modem on the WAN side click on the
Advanced setup Menu and then click on the WAN.
 PPPoE Configuration
• To create a PPPoE Service Click on Add Button.

Modem Configuration
 PPPoE Configuration on the Modem
 Assign VPI=0 and VCI=35 as shown in the Screen below
and Click on Next button

 Select the Connection type PPPoE and
Encapsulation LLC/SNAP-Bridging as shown in
the picture below and then Click on Next Button
Modem Configuration

Modem Configuration
 Enter the Username, Password and other information provided by
your service provider and click the Next button as shown in the
picture below. Example: PPP Username = ABCDE, PPPPassword
= ABCDE and PPPoE Service Name=12345(if Provided by ISP)

Modem Configuration
 The following screen displays the configuration summary.
Click the Save button to save the setting.
 If any further changes are needed then Click the Back
button to do further Modifications.

Modem Configuration
 After clicking on the Save the configuration will be saved and
the following Screen will be displayed.
 Here click on Save and Reboot Button to activate the
configuration changes.

Modem Configuration
 Bridge Configuration on the Modem
 Bridge Configuration
• To create a Bridge Service Click on Add Button from the
Advanced Setup  WAN

Modem Configuration
 Assign VPI=0 and VCI=35 as shown in the Screen below
and Click on Next button

Modem Configuration
 Select the Connection type Bridge and Encapsulation
LLC/SNAP-Bridging as shown in the picture below and then
Click on Next Button

Modem Configuration
 In the following screen ensure that the ENABLE Bridge
Service check box is selected and then Click the Next
button.

Modem Configuration
 The following screen displays the configuration summary.
Click the Save button to save the setting.
 If any further changes are needed then Click the Back
button to do further Modifications.

Modem Configuration
 After clicking on the Save the configuration will be saved
and the following Screen will be displayed.
 Here click on Save and Reboot Button to activate the
configuration changes.

Wireless Configuration
 Type II modems functions as a Wireless Access Point
enabling Wi-Fi capable LAPTOPs to access Internet or other
PCs connected on to the Modem.
 The forthcoming slides illustrate how to configure the
Wireless portion on the Modem.

 To configure the Wireless Section click on the Wireless Button
 This will open the Wireless Basic configuration page as shown inthe
Picture below.
 Enter the name of the Access Point SSID, Check the “Enable Access
Point” check box and select theCountry.
 After making the changes click on Save and Apply. By default Wireless
section is configured with SSID as INDIA, Country as India. And it is also
enabled by default.

 Network Authentication and Data Encryption for the Wireless section cane
be configured by clicking on the Security Button under wireless section as
shown in the Picture below. This is for Secure communication from the
PCs to the Modem.
 Use the Pull down Menu to configure the required optionsfor
Authentication and Encryption

 Using MAC Filter option under the Wireless Section Menu Nodes or PCs
can be restricted. This is to prevent Un authorized access to the Modem. In
the Menu Below click on the Add and then enter the MAC Addresses of the
PCs that are allowed to access the Internet.
 For Advanced options refer to the User Manual supplied with the Modem.

HOW TO SECURE YOUR WIRELESS
BROADBAND NETWORK
Changing the Configuration Page's Password
Every wireless router or access point comes with a built-in
configuration page, this will look like an internal web page that
is accessed from your web browser. Usually, the password is
either blank or says something along the lines of ?admin.?
Changing both the username as well as the password is an
important step in keeping your wireless broadband connection
secure.
Disabling the Broadcasting of Your SSID(Service Set Identifier)
Most wireless broadband access points and routers make their
SSID public. While this makes it easy to connect to the network,
it also announces to everyone that you are using a wireless
network. Disabling this broadcasting prevents others from
easily knowing that you are using a wireless network for your
broadband connection.

HOW TO SECURE YOUR WIRELESS
BROADBAND NETWORK
Changing the Default IP Number of the Wireless Access Point
or Router
Change the default IP number to something different so hackers
cannot easily find the configuration menu. The default IP
number is something the manufacturer's put in to make the
system easy to use. All hackers are familiar with the default IP
number, so changing it will help secure your wireless system.
Enabling WEP or WPA Encryption
With the WEP (Wired Equivalent Privacy) or WPA (Wi-Fi
Protected Access) box options checked off, a user has to have a
correct encryption key to connect to the wireless network. WEP
comes with different encryption levels, and the higher the level,
the more difficult it is to break the encryption code.

COMMON ERRORS IN THE BROADBAND
AND THEIR RESOLUTION
Error-678
This is most common problems. It is due to poor
connectivity. Problem can be anywhere between
B.RAS - Tier 2 - DSLAM - Modem - PC of the
customer.
Switch off / Switch on Modem (Power Switch at the
back of modem ) and wait for 2 minutes. Then retry.
Error-691
User id and Password problem.
The case is to be referred to Central Broadband
Team. Central Broadband Team will reset the
password and intimate that password has been reset.

Error-769
LAN not enabled.
The LAN Card has to be enabled by following the
steps given below.
i)Go to Desktop.
ii)Click "My Network Place".
iii)Select Properties.
iv)Click "Enable the local network"

Error- 797
Modem or LAN driver problem.
Reset the Modem (in on condition ) by pressing button
available in the backside hole of the modem and wait for 2
mintues and then log on. If the problem is not solved then
call your vendor to check computer LAN Card driver.
Error-718
i)Peak Hour - This problem occurs if loading is high on the
system and number of customers exceed the call handling
capacity of B.RAS. ii)Slack Hour -This problem occurs if
PPPoE is corrupted.
i)Peak Hour - Please try after some time. ii)Slack Hour -
Please load PPPoE again.

Error - 630-633
Computer LAN Card problem.
LAN Card has to be changed.
Site not opening
From Broadband connection, sites are not opening.
Probable reasons i)Internet explorer is not supporting
the Pop (may be pirated OS). ii)Virus has corrupted
the Internet explorer.
The user has to set it right by re-installing the O/S or
Internet Browser(I.E. etc).

dmt modulation cpe security in wifi Dsl adsl cpe conf

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